Is it possible to estimate a light source wattage remotely?

[Alfreds9]

I'd like to know if it's possible to roughly estimate a light source wattage remotely, knowing the distance and perhaps estimating that at such a distance it's still above the minimum human recognizable threshold at night (in a light polluted area).

Maybe using a DSLR camera could help by checking on computer the value difference between "dark" (actually soil, which should still have some reflectange given by light pollution) and "light" pixel values?

Thank you

 

[Simon Bridge]

Yes it is ... this is how the power output of stars is figured out.
You need a decent model for how the source emits light, and some measure of how much light is arriving.